Controlled Induced Warping of Electronic Substrates via Electroplating

ABSTRACT

An integrated circuit (IC) package incorporating controlled induced warping is disclosed. The IC package includes an electronic substrate having an active side upon which semiconducting dies and functional circuits have been lithographed or otherwise fabricated, leading to an inherent warping in the direction of the active side. One or more corrective layers may be deposited to the opposing, or inactive, side of the semiconducting die via electroplating in order to induce corrective warping of the electronic substrate back toward the horizontal (e.g., in the direction of the inactive side) to a desired degree.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 120 as acontinuation-in-part of co-pending U.S. patent application Ser. No.16/750,382, filed Jan. 23, 2020, entitled CONTROLLED INDUCED WARPING OFELECTRONIC SUBSTRATES. Said U.S. patent application Ser. No. 16/750,382is herein incorporated by reference in its entirety.

TECHNICAL FIELD

The subject matter disclosed herein is directed generally to electroniccircuitry and more particularly to semiconducting dies upon whichfunctional circuits are fabricated.

BACKGROUND

Integrated circuit (IC) packages are small blocks of semiconductingmaterial upon which semiconducting dies and/or functional circuits arefabricated, e.g., via lithography, additive manufacturing, etc. Forexample, when a functional circuit is built on the active side of thepackage, remnant internal stresses will be induced in the substratecausing warping in the direction of the active layer. Warping of up to25% of the package thickness has been observed. Warping in the packageor its components may lead to further manufacturability issues, e.g.,during lithography or spin-on operations. Additionally, warped packagesintegrated into end products may experience opens, head-on-pillowdefects, and other die interconnect issues which may lead to electricalfailures. Finally, package warping may complicate or prevent z-heightminiaturization efforts by requiring mechanical designs to accommodatethe warping. There is currently no method for addressing thesechallenges via the flattening of warped packages.

SUMMARY

An integrated circuit (IC) package is disclosed. In embodiments, the ICpackage includes one or more electronic substrate layers having anactive side (e.g., face) and an inactive side opposite the active side,one or more semiconducting dues and/or functional circuitry fabricatedon the active side. The IC package is subject to a degree of inherentwarping toward the active side, the warping associated with thefabrication of the die and functional circuitry. To induce a desireddegree of counter-warping of the electronic substrates toward theinactive side, the inactive side (e.g., face) may have one or morecorrective layers deposited thereon via electroplating or other likeelectrodeposition techniques.

In some embodiments, a conductive seed layer or layers is deposited overthe inactive side, and the corrective layers deposited over the seedlayer.

In some embodiments, the electrodeposition of the corrective layers isdependent on one or more predetermined parameters.

In some embodiments, the thickness of the corrective layer or layers isbased on the predetermined parameters.

In some embodiments, the rate of electrodeposition of the correctivelayer or layers is based on the predetermined parameters.

In some embodiments, the predetermined parameters are associated withthe semiconducting die, the electronic substrate, and the determineddegree of inherent warping therein.

In some embodiments, the predetermined parameters are associated withthe corrective layers (e.g., material composition) or the desired degreeof induced warping.

In some embodiments, the corrective layers include one or more ofsubstantially elemental metallic components and metallic alloycomponents.

In some embodiments, the desired degree of induced warping is atemporary warping, and the corrective layers are fully or partiallyremovable.

In some embodiments, the inherent warping is detected or identifiedwithin selected portions of the surface area of the electronicsubstrate, and the corrective layers applied to the selected warpedportions.

A method for induced warping of an IC package or its components is alsodisclosed. In embodiments, the method includes determining a degree ofinherent warping toward an active side of an electronic substrate of theIC package, the inherent warping associated with the fabrication ofsemiconducting die/s and functional circuitry upon the active side. Themethod includes determining a degree of desired induced warping stress(e.g., counter-warping) toward an inactive side of the electronicsubstrate, the inactive side opposite the active side. The methodincludes applying one or more conductive seed layers to the inactiveside. The method includes implementing the desired induced warpingstress by applying, via electroplating or electrodeposition, at leastone corrective layer over the seed layers on the inactive side.

In some embodiments, the method includes determining one or moreparameters based on the semiconducting die, the electronic substrate,the determined degree of inherent warping therein, the corrective layeror layers, and the desired warping stress to be induced within theelectronic substrate. The corrective layer or layers are applied overthe seed layers based on these determined parameters.

In some embodiments, the method includes applying the corrective layeror layers at a predetermined rate based on the determined parameters.

In some embodiments, the method includes applying the corrective layeror layers to a predetermined thickness based on the determinedparameters.

In some embodiments, the method includes determining the degree ofinherent warping with respect to selected portions of the electronicsubstrate, and applying the seed layers over the selected portions.

In some embodiments, the method further includes partially or fullyrestoring the inherent warping by removing the corrective layer orlayers, e.g., via electropolishing.

This Summary is provided solely as an introduction to subject matterthat is fully described in the Detailed Description and Drawings. TheSummary should not be considered to describe essential features nor beused to determine the scope of the Claims. Moreover, it is to beunderstood that both the foregoing Summary and the following DetailedDescription are example and explanatory only and are not necessarilyrestrictive of the subject matter claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. The use of the same reference numbers in different instances inthe description and the figures may indicate similar or identical items.Various embodiments or examples (“examples”) of the present disclosureare disclosed in the following detailed description and the accompanyingdrawings. The drawings are not necessarily to scale. In general,operations of disclosed processes may be performed in an arbitraryorder, unless otherwise provided in the claims. In the drawings:

FIG. 1 is a diagrammatic cross section illustrating an integratedcircuit (IC) package in accordance with example embodiments of thisdisclosure;

FIG. 2 is a diagrammatic cross section illustrating the IC package ofFIG. 1;

FIGS. 3A through 3C are diagrammatic cross sections illustrating inducedwarping operations of the IC package of FIG. 1;

FIG. 4 is a diagrammatic cross section illustrating operations on the ICpackage of FIG. 1;

FIG. 5 is a flow diagram illustrating a method for induced warping of anIC package in accordance with example embodiments of this disclosure;

FIGS. 6A through 6C are diagrammatic cross sections illustrating an ICpackage configured for corrective warping via electrodeposition inaccordance with example embodiments of this disclosure;

FIGS. 7A and 7B are diagrammatic overhead views of an IC packageconfigured for portional corrective warping in accordance with exampleembodiments of this disclosure;

and FIG. 8 is a flow diagram illustrating a method for induced warpingof an IC package in accordance with example embodiments of thisdisclosure.

DETAILED DESCRIPTION

Before explaining one or more embodiments of the disclosure in detail,it is to be understood that the embodiments are not limited in theirapplication to the details of construction and the arrangement of thecomponents or steps or methodologies set forth in the followingdescription or illustrated in the drawings. In the following detaileddescription of embodiments, numerous specific details may be set forthin order to provide a more thorough understanding of the disclosure.However, it will be apparent to one of ordinary skill in the art havingthe benefit of the instant disclosure that the embodiments disclosedherein may be practiced without some of these specific details. In otherinstances, well-known features may not be described in detail to avoidunnecessarily complicating the instant disclosure.

As used herein a letter following a reference numeral is intended toreference an embodiment of the feature or element that may be similar,but not necessarily identical, to a previously described element orfeature bearing the same reference numeral (e.g., 1, 1 a, 1 b). Suchshorthand notations are used for purposes of convenience only and shouldnot be construed to limit the disclosure in any way unless expresslystated to the contrary.

Further, unless expressly stated to the contrary, “or” refers to aninclusive or and not to an exclusive or. For example, a condition A or Bis satisfied by any one of the following: A is true (or present) and Bis false (or not present), A is false (or not present) and B is true (orpresent), and both A and B are true (or present).

In addition, use of “a” or “an” may be employed to describe elements andcomponents of embodiments disclosed herein. This is done merely forconvenience and “a” and “an” are intended to include “one” or “at leastone,” and the singular also includes the plural unless it is obviousthat it is meant otherwise.

Finally, as used herein any reference to “one embodiment” or “someembodiments” means that a particular element, feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment disclosed herein. The appearances of thephrase “in some embodiments” in various places in the specification arenot necessarily all referring to the same embodiment, and embodimentsmay include one or more of the features expressly described orinherently present herein, or any combination or sub-combination of twoor more such features, along with any other features which may notnecessarily be expressly described or inherently present in the instantdisclosure.

Referring to FIG. 1, an integrated circuit (IC) package 100 isdisclosed. The IC package 100 may include electronic substrates 102 andan active layer 104 upon which one or more semiconducting dies 106and/or additional functional circuitry may be fabricated.

In embodiments, the electronic substrates 102 may be fashioned ofsilicon or any other appropriate semiconducting material. The activelayer 104 may include, for example, additive layers or other functionalcircuitry fabricated upon the electronic substrates 102 (e.g., onto anactive side of the electronic substrate) or upon any additive layersdeposited thereon, resulting in an inherent warping 108 toward theactive layer (e.g., due to internal compressive stressed within theactive layer). An induced warping stress may be imparted to the ICpackage 100 by utilizing thin film deposition (TFD) instrumentation todeposit (110) or bond one or more corrective layers 112 on the inactiveside (114) of the electronic substrates 102 (e.g., the side opposite theactive layer/active side 104). As the corrective layers 112 are appliedto the inactive side 114 of the electronic substrates 102 (e.g., andcondense thereon as thin films), the functionality of the active layer104 is unaffected. For example, depending on the desired degree ofinduced warping (and, e.g., the corresponding amount of compressive ortensile stress to induce within the active layer 104), the correctivelayers 112 may be deposited via physical vapor deposition (PVD),sputtering deposition, electroplating, or any other like instrumentationand process.

Referring also to FIG. 2, the IC package 100 a may be implemented andmay function similarly to the IC package 100 of FIG. 1, except thatresidual stresses within the corrective layers 112 bonded to theinactive side 114 may induce compressive stresses (116 a) and/or tensilestresses (116 b) contributing to correctively warp (116) the electronicsubstrates 102 of the IC package 100 of FIG. 1 in the direction of theinactive side 114, such that the electronic substrates 102 and/orsemiconducting die 106 are warped into a horizontal or near-horizontalorientation (as shown by the IC package 100 a of FIG. 2).

In embodiments, the precise direction and amount of induced warpingnecessary to achieve the substantially horizontal IC package 100 a maydepend on a variety of parameters. For example, the material compositionas well as the thickness and dimensions (e.g., x/y) of the electronicsubstrates 102 and/or semiconducting die 106 may affect the necessarydirection and degree of induced warping 116 to correct the inherentwarping (108, FIG. 1). Similarly, parameters may also be determined foroptimal deposition of the corrective layers 112. For example, thecorrective layers 112 may include copper or other metallic elements,alloys, or compounds. In some embodiments, the corrective layers 112 mayinclude ceramic layers, metalloids, amorphous (e.g., glassy)semiconducting materials, or any appropriate combinations thereof. Byselecting corrective layers 112 of a particular thickness and depositingthe corrective layers to the inactive side 114 at a particulardeposition rate (e.g., between 5 Angstroms per second (Å/s) and 120Å/s), significant corrective deflections of the electronic substrates102 may be achieved. For example, higher deposition rates of correctivelayers 112 primarily comprising copper may be associated with higherresidual stresses and therefore higher degrees of induced warping 116.Similarly, the number of corrective layers 112 deposited may be selectedwith a particular degree of induced warping 116 in mind, as describedbelow.

In some embodiments, determination of the optimal deposition parametersand deposition of the corrective layers 112 may occur during the activelayer manufacturing phase of the production process of the IC package100 a. In other embodiments, parameter determination and deposition ofthe corrective layers 112 may occur during other phases of theproduction process or based on other types of IC package 100 a, e.g.,during reflow soldering or in response to warping issues associated withflip-chip packages and thin ball grid arrays.

Referring also to FIGS. 3A through 3C, the IC packages 100 b-c may beimplemented and may function similarly to the IC packages 100, 100 a ofFIGS. 1 and 2, except that the IC packages 100 b-c may incorporatemultiple corrective layers 112 a-n deposited on the inactive side 114via TFD (e.g., at lower deposition rates (e.g., 5 Å/s or less) so as tominimize impact stress). For example, referring in particular to FIG.3A, a first corrective layer 112 a may be bonded (110 a) to the inactiveside 114 of the IC package 100 b at a particular deposition rate.Referring in particular to FIG. 3B, a second corrective layer 112 b maybe deposited upon (110 b) or bonded to the first corrective layer 112 a,inducing a further warping 116 a-b of the IC package 100 b. Referring inparticular to FIG. 3C, the continued deposition of multiple correctivelayers 112 a-n may provide, through each successive corrective layer,additional induced warping (116 a-b) toward the inactive layer 114 suchthat the inherent warping (108, FIG. 1) of the IC package 100 b may bereduced or even reversed, resulting in the substantially horizontal ICpackage 100 c shown by FIG. 3C.

Referring to FIG. 4, the IC package 100 d may be implemented and mayfunction similarly to the IC packages 100, 100 a-c of FIGS. 1 through3C, except that one or more corrective layers 112 a-n may be removablelayers configured for temporary induced warping. For example, an outercorrective layer 112 n may be partially or fully removed (402) from theelectronic substrate 102, fully or partially relieving the correspondinginternal compressive and tensile stresses and thereby relieving thecorresponding induced warping (116 a-b, FIGS. 3B-C).

Referring to FIG. 5, the method 500 for induced warping of an integratedcircuit (IC) package may be implemented with respect to the IC packages100, 100-d of FIGS. 1 through 4, and may incorporate the followingsteps.

At a step 502, the degree of inherent warping toward the active side ofan electronic substrate of the IC package due to the fabrication of asemiconducting die and/or functional circuitry on the active side isdetermined. For example, parameters associated with the semiconductingdie or with the electronic substrates may be determined, e.g., thedimensions of the substrate, the thickness of the substrate, or thematerial composition of the substrate.

At a step 504, a desired degree of induced warping stress toward theinactive side (e.g., opposite the active side) of the electronicsubstrate is determined. For example, the desired material compositionof corrective layers applicable to the inactive side to correctivelywarp the substrate to the desired degree may be determined, as well asthe desired number of layers to be applied (if more than one correctivelayer is to be applied).

At a step 506, the desired degree of induced warping stress isimplemented by applying at least one corrective layer to the active sidevia thin film deposition (TFD). For example, the corrective layer/s maybe applied at a predetermined deposition rate, or to a predeterminedthickness, based on the determined parameters.

The method 500 may include an additional step 508. At the step 508, aportion (partial or full) of the at least one applied corrective layeris partially or fully removed from the inactive side upon which it wasdeposited to remove the corresponding induced warping stress.

Referring now to FIG. 6A, the IC package 600 may be implemented and mayfunction similarly to the IC packages 100, 100 a-d of FIGS. 1 through 4,except that the IC package 600 may be configured for corrective warpingvia electroplating or any appropriate like means of electrophoreticdeposition (EPD). The IC package 600 may include electronic substrates102, active layer 104, and one or more semiconducting dies 106.

In embodiments, one or more conductive seed layers 602 may be applied tothe electronic substrates 102 on its inactive side 114. For example, theinactive side 114 may not incorporate conductive materials sufficient tosupport EPD.

Referring also to FIG. 6B, the IC package 600 a may be implemented andmay function similarly to the IC package 600 of FIG. 6A.

In embodiments, the IC package 600 a may have one or more correctivelayers 112 deposited thereon via electroplating or EPD. By way of anon-limiting example, the IC package 600 a may be immersed in anelectrolytic solution 604 along with a consumable metal anode 606 (e.g.,copper, gold, nickel, or any other substantially elemental metal ormetallic alloy suitable for EPD). A direct current 608 directed to theanode 606 may cause its component metal/s to dissolve into theelectrolytic solution 604. The seed layer 602 may serve as a cathodeupon which the dissolved metal ions plate, or deposit onto (610), at adesired rate (and/or, e.g., to a desired thickness) based onpredetermined parameters as described above.

Referring also to FIG. 6C, the IC package 600 b may be implemented andmay function similarly to the IC packages 600, 600 a of FIGS. 6A-B,except that the IC package 600 b may undergo corrective warping (116)due to the application of the corrective layer/s 112. For example, theIC package 600 b may be correctively warped 116 to a horizontal ornear-horizontal orientation, or to a greater or lesser degree based onpredetermined parameters as described above.

Referring to FIGS. 7A and 7B, the IC package 700 may be implemented andmay function similarly to the IC packages 100, 600 of FIGS. 1 through6C, except that the IC package 700 may experience interconnect defects702 (e.g., inherent warping, opens, head-on-pillows) within determinabledefective portions 704 of the electronic substrates 102 (as opposed tothroughout the entire substrate).

In embodiments, the IC package 700 may be correctively warped on aportional bases to counteract interconnect defects 702 on a targeted orselective basis. For example, warping parameters may be determined(e.g., with respect to one or more of the composition of the electronicsubstrates 102 or the semiconducting die 104, the nature and magnitudeof the observed interconnect defects 702, the composition of thecorrective layer/s 112, or the desired degree of corrective warping 116and, per the determined parameters, seed layers 602 applied to thedefective portions/s 704 on their inactive side 114.

In embodiments, the corrective layers 112 may be electrophoricallydeposited over the seed layers 602 to selectively induce correctivewarping 116 within the defective portions 704 of the IC package 700. Insome embodiments, the defective portions 704 may be correctively warped116 via the application of corrective layers 112 via TFD as describedabove. Similarly, in some embodiments the corrective layers 112, or someportion thereof, may be removed (e.g., via electropolishing) to restoresome or all of the inherent warping stress (108, FIG. 1).

Referring to FIG. 8, the method 800 for induced warping of an integratedcircuit (IC) package may be implemented with respect to the IC packages600, 700 of FIGS. 6A through 7B, and may incorporate the followingsteps.

At a step 802, a degree of inherent warping (or, more generally,interconnect defect) is determined. For example, the inherent warp orinterconnect defect may orient toward, an active side of an electronicsubstrate and may result from the fabrication of at least one of asemiconducting die and functional circuitry upon the active side. Insome embodiments, the inherent warping may be present in only a portionof the electronic substrate.

At a step 804, a desired degree of corrective warping stress to induceis determined based on one or more parameters. For example, the desireddegree of corrective warping may be based on one or more of thecomposition of the semiconducting die, the electronic substrate, or thecorrective layers; the degree of inherent warping or interconnectdefect; or the desired induced warping stress.

At a step 806, one or more conductive seed layers are applied to theinactive side of the IC package.

At a step 808, the desired warping stress is implemented by applying thecorresponding corrective layers via electrodeposition upon the seedlayers. For example, the corrective layers may be applied according toone or more predetermined parameters, e.g., the rate at which thecorrective layers are applied, or the thickness of the correctivelayers. In some embodiments, the corrective layers (as well as theconductive seed layers) may be applied only to selected portions of theinactive side.

The method 800 may include an additional step 810. At the step 810, theinherent warping may be partially or fully restored by removing thecorrective layers via electropolishing or any like appropriate means ofremoval.

CONCLUSION

It is to be understood that embodiments of the methods disclosed hereinmay include one or more of the steps described herein. Further, suchsteps may be carried out in any desired order and two or more of thesteps may be carried out simultaneously with one another. Two or more ofthe steps disclosed herein may be combined in a single step, and in someembodiments, one or more of the steps may be carried out as two or moresub-steps. Further, other steps or sub-steps may be carried in additionto, or as substitutes to one or more of the steps disclosed herein.

Although inventive concepts have been described with reference to theembodiments illustrated in the attached drawing figures, equivalents maybe employed and substitutions made herein without departing from thescope of the claims. Components illustrated and described herein aremerely examples of a system/device and components that may be used toimplement embodiments of the inventive concepts and may be replaced withother devices and components without departing from the scope of theclaims. Furthermore, any dimensions, degrees, and/or numerical rangesprovided herein are to be understood as non-limiting examples unlessotherwise specified in the claims.

What is claimed is:
 1. An integrated circuit (IC) package, comprising:at least one semiconducting die; an electronic substrate having anactive side and an inactive side opposite the active side, at least oneof the semiconducting die and functional circuitry fabricated on theactive side, at least one of the semiconducting die and the electronicsubstrate associated with an inherent warping toward the active side,and the inactive side having at least one corrective layer depositedthereupon via electrodeposition, the at least one corrective layerconfigured for desired induced warping of the electronic substratetoward the inactive side.
 2. The IC package of claim 1, wherein: atleast one conductive seed layer is deposited over the inactive side; andthe at least one corrective layer is deposited upon the at least oneseed layer.
 3. The IC package of claim 1, wherein the at least onecorrective layer is deposited based on at least one predeterminedparameter.
 4. The IC package of claim 3, wherein the at least onecorrective layer is deposited to a predetermined thickness based on theat least one predetermined parameter.
 5. The IC package of claim 3,wherein the at least one corrective layer is deposited at apredetermined rate based on the at least one predetermined parameter. 6.The IC package of claim 3, wherein the at least one predeterminedparameter corresponds to at least one of the semiconducting die, theelectronic substrate, and the inherent warping.
 7. The IC package ofclaim 3, wherein the at least one predetermined parameter corresponds toat least one of the corrective layer and the desired induced warping. 8.The IC package of claim 1, wherein the at least one corrective layer isselected from a metallic layer and a metallic alloy layer.
 9. The ICpackage of claim 1, wherein: the desired induced warping includes atemporary induced warping: and the at least one corrective layer is atleast partially removable.
 10. The IC package of claim 1, wherein: theinactive side corresponds to a surface area; the inherent warping of theelectronic substrate corresponds to one or more warped portions of thesurface area; and the at least one corrective layer is applied to theone or more warped portions.
 11. A method for induced warping of anintegrated circuit (IC) package, the method comprising: determining adegree of inherent warping toward an active side of an electronicsubstrate, the inherent warping associated with a fabrication of atleast one of a semiconducting die and functional circuitry upon theactive side; determining a degree of desired induced warping stresstoward an inactive side of the electronic substrate, the inactive sideopposite the active side; applying at least one conductive seed layer tothe inactive side; and implementing the desired induced warping stressby applying, via electrodeposition, at least one corrective layer to theseed layer.
 12. The method of claim 11, wherein: determining a degree ofdesired induced warping stress toward an inactive side of the electronicsubstrate, the inactive side opposite the active side, includes:determining at least one parameter corresponding to at least one of thesemiconducting die, the electronic substrate, the degree of inherentwarping, the corrective layer, and the desired induced warping stress;and implementing the desired induced warping stress by applying, viaelectrodeposition, at least one corrective layer to the seed layerincludes: applying the at least one corrective layer to the seed layerbased on the at least one determined parameter.
 13. The method of claim12, wherein implementing the desired induced warping stress by applying,via electrodeposition, at least one corrective layer to the seed layerincludes: applying the at least one corrective layer at a predeterminedrate based on the at least one determined parameter.
 14. The method ofclaim 12, wherein implementing the desired induced warping stress byapplying, via electrodeposition, at least one corrective layer to theseed layer includes: applying the at least one corrective layer to apredetermined thickness based on the at least one determined parameter.15. The method of claim 11, wherein: determining a degree of inherentwarping toward an active side of an electronic substrate includesdetermining the degree of inherent warping within one or more warpedportions of the electronic substrate; and applying at least oneconductive seed layer to the inactive side includes applying theconductive seed layer to the one or more warped portions.
 16. The methodof claim 11, further comprising: at least partially restoring theinherent warping by at least partially removing the at least onecorrective layer via electropolishing.